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Understanding soil moisture variability and estimating high‐resolution soil moisture at subfield to field scales is critical for agricultural research and applications. However, systematic investigation of subfield scale soil moisture variability over cropland is still lacking from both measurement and satellite remote sensing. In this study, we aim to investigate (1) the characteristics of within‐field soil moisture distribution over typical cropland in the US Midwest and (2) the capabilities of satellite remote sensing in capturing the spatiotemporal variabilities of soil moisture at subfield scale. Specifically, we conducted soil moisture field experiments in three typical commercial agricultural fields (∼85 acres per field) in central Illinois, representing typical commercial farmlands in the US Midwest, and compared the soil moisture measurements with satellite remote sensing data from optical and active microwave sensors. In each field, dense soil moisture samples (spaced at 50–60 m) were obtained for two dry down events in May and July 2021, and multiple long‐term soil moisture stations were installed. We found prominent time‐invariant spatial structures of soil moisture at within‐field scales both during the dry down period and over longer time scales, and the stability is minimally affected by plant water use during the growing season. Comparing the field campaign measurements with satellite remote sensing data, we found that surface reflectance of shortwave infrared bands, such as SWIR1 (1610 nm) from Sentinel‐2, can capture relative surface soil moisture patterns at within‐field scales, but their relationships with soil moisture are field specific. These findings and the improved understanding of within‐field soil moisture dynamics could potentially help future research on high‐resolution soil moisture estimation with multi‐source remote sensing data. Core Ideas: High‐density soil moisture sampling was conducted in agricultural fields.Time‐invariant spatial structures of within‐field soil moisture were evaluated.Strong but field‐specific relationships between soil moisture and optical remote sensing were found.A pathway for remote sensing based high‐resolution soil moisture estimation was proposed. [ABSTRACT FROM AUTHOR]

Measurement of planktonic chlorophyll‐a—a proxy for algal biomass—in rivers may represent local production or algae transported from upstream, confounding understanding of algal bloom development in flowing waters. We modeled 3 years of chlorophyll‐a transport through a 394‐km portion of the Illinois River and found that although algal biomass is longitudinally widespread, most net production occurs at river control points in the upper reaches (up to 3.7 Mg chlorophyll‐a y−1 km−1). Up to 69% of the algal biomass in the upper river was a result of within‐reach production, with the remainder recruited from headwaters and tributaries. High chlorophyll‐a measured farther downstream was largely because of transport from source‐area control points, with substantial net losses of algal biomass occurring in the lower river. Modeling the often‐overlooked river transport component is necessary to characterize where, when, and why planktonic algae grow and predict how far and fast they move downstream. Plain Language Summary: Planktonic algae in rivers may accumulate during periods of high productivity stimulated by favorable light, temperature, nutrient, and flow conditions, which can disrupt ecological processes and affect human uses including recreation and drinking water supply. Planktonic algae observed in rivers may occur because of local growth or transport from upstream source areas. Therefore, considering both local and upstream conditions may improve early warnings of potentially harmful blooms. Along a 394‐km stretch of the Illinois River, we found that most of the algae grew in the upper reaches and was then transported to downstream reaches, contributing to potential downstream harms such as excessive turbidity, organic carbon, biological oxygen demand, and algal toxins. We demonstrate how the often‐overlooked river transport component can be quantified to better identify where, when, and why algae grow in river networks. Key Points: Planktonic algal biomass is pervasive in the Illinois River, yet production is favored at certain locations and timesMost planktonic algal biomass was produced in upper‐reach control points that supplied downstream areasTransport analysis using local and upstream data improves understanding of river algal blooms [ABSTRACT FROM AUTHOR]

Aspergillus fungi are ubiquitous inhabitants of colonies of the western honey bee (Apis mellifera), where they interact with bees in associations ranging from parasitism to possible mutualism. Aspergillus Flavi fungi are frequently found in bee bread (pollen processed for longterm storage) and are thought to contribute to food preparation, processing, preservation, and digestion. Conditions in the hive are challenging for fungi due, in part, to xeric and acidic properties of bee bread and the omnipresence of propolis, an antimicrobial product manufactured by bees from plant resins. We used quantitative and qualitative assays to determine whether A. flavus isolated from bee bread demonstrates tolerance for hive environmental conditions in terms of temperature, pH, osmotic pressure, and propolis exposure. Comparisons made use of three strains of A. flavus: a fungal biocontrol product not known from beehives (AF36), a strain isolated from bee bread (AFBB) in hives from central Illinois, and a pathogenic strain from a honey bee colony displaying symptoms of stonebrood (AFPA). Strain AFBB displayed higher tolerance of acidic conditions, low matric potential (simulating xeric substrate), and propolis exposure than did other strains. A genomic comparison between this new strain and the reference NRRL‐3357 showed that AFBB, like AF36, might be blocked from carrying out aflatoxin biosynthesis. Sequence comparisons also revealed several missense variants in genes that encode proteins regulating osmotolerance and osmotic pressure in Aspergillus spp., including SakA, SskB, GfdA, and TcsB/Sln1. Collectively, results of our laboratory assays and genetic analyses are consistent with the suggestion that the strain isolated from bee bread is adapted to the bee bread environment and may have persisted due to a coevolutionary relationship between Aspergillus and A. mellifera. This finding bolsters recent concerns about the effects of fungicide use near bee colonies and broadens the ecological importance of highly adaptable fungal strains. [ABSTRACT FROM AUTHOR]